add the comment to link the specification

[FYL2003]

The change is uploaded.

[coveralls]

Pull Request Test Coverage Report for Build 9462598144

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 81.532%

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Totals
Change from base Build 9342753382:	0.0%
Covered Lines:	10933
Relevant Lines:	13042

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💛 - Coveralls

[martin-henz]

It seems that this PR is not difficult to fix so that it can be merged. @FYL2003 can you take another look please.